Treatment of cellulosic bodies



'Patented July 6, 1931 Wilmington, Del,

asslguors to E. I. du Pont de Nemours 6; Company, Wilmington, Del., a.corporation of Delaware No Drawing. Application September 4, 1934,Serial No. 2,692

deterloretlon of organlc materials and more partlculorlv to thestabilizing of cellulose, cellulose manufactures and chemicalderivatives of cellulose.

It hes been discovered. that deterioration of the above materialscambelefiectively retarded by treating them with smell-'emouuts ofcertain, stshlllmng chemical agents, namely, polycyclic phenols havingat least two non-cohdensed carbocycllc nuclei. memplesof *suofiphenolsare p-hydroxy-dipheuyl and p jcycloheml phenol.

The deterlorstlon oi celliiloslc substances such as those with whichthe"preseut invention is concerned seems to be induced or accelerated bylight, particularly ultraviolet light. In other words, the deteriorationseems in many lnstcnces to he photochemical since its rapidityfrequently varies dlrectly with the intensity of the light.

In the absence of light this deterioration is often very slow andimperceptible except over long periods ct time but takes place,nevertheless, as evidenced by the dlscoloretion and weak: suing ofpaper, hooks, cotton fabrics, newspaper files, etc, even when stored. indork places at comparatively low temperatures. Thus, while the rate ofdeterioration may very vvlth the pertlcular conditions, the presentagents will be lcuud efiective for retarding lt under any given set ofconditions. However, neither the nature of the deterioration ofcelluloslc substances (whether hydrolytlc, ofidetlve or otherwise) northe manner in which the present agents functies to prevent it isdefinitely known, and it is not desired to be confined to any theory,thereof.

The general object of this invention is therefore to provide methods forretarding the deleterious efiects of aging on paper, cellulosic fabrlcs,sud various other celluloslc materials. A pertlculer object of thislnventlon is to provide methods of decreasing the deterioration, due toor lmtlated by ultrevlclet'rays and other causes, of these celluloslcsubstances included in the group consisting of regenerated cellulose,cellulose others and organic sold esters of cellulose. The materials mayhe in the form of fibers, storms-lawns, and thin sheets of differentsizes, shapes and transparency. Examples of cellulose esters with whichthe present agents may be used effectively are cellulose acetate,cellulose butyrste, cellulose "laurate, cellulose isobutyrate,

cellulose propionate, etc. Examples of cellulose ethers are methylcellulose, ethyl cellulose, benzyl cellulose, dodecyl cellulose, propylcellulose, clnnamyl cellulose. glycol cellulose, and

(or. or-so) cellulose glycolllc acid. The cellulose esters and othersmay be of the high or low substituted types, having for example from onesubstltuent group for eight glucose units up to three substltuent groupsfor each. glucose unit.

Another object of this invention is to provide methods of retarding thedeteriorating effect of aging on, various cellulose manufacturesincluded in a, group comprising paper, cotton filaments and woven and.knitted fabrics such as cotton, 10 linen, remle, jute, etc. Theseobjects are accompllshed by treating paper, cotton goods and the otheraforementioned cellulodc materials with a. polycyclic phenol having atleast two non-condensed carbocycllc, nuclei, which compounds 5 have theproperty of stabilizing the celluloslc materials against the injuriousefiect of aging or exposure to concentrated ultraviolet rays.

Other objects of this invention and methods forthelr attainment will beapparent as the description proceeds.-

These objects are accomplished by treating paper, cotton goods, andother aforementioned celluloslc materials with a. polycyclic phenolhavlug at least two non-condensed cerbocycllc nuclei', as illustrated inexamples which follow.

Specific examples of some of the suitable stabilizing egeuts that fellwithin the scope of this invention are the following phenols which, aswill be seen, are of two types, those having non-condensed aromaticnuclei and those havlog on allcyclic ring.

Non-condensed polycyclic phenols with only aromatic nucleio-Hydroxydiphenyl m-Hydroxydiphenyl p-liydroxydiphenyo,o'-Dlhydroxyd1phenyl 40 mm'-Dlhydroxydrphenyl 'Dl (l-hydroxyphenyl)-phenylmethane Di(4-hydroxypheny1) dlm'ethylmethsne131(4-hydroxynephthyl) dlmethylmethane BN3 methyl 4 hydromheuyl)dlmethylmethone Di(4-hydroxyphenyl) methylethylmethane Biol hydroxy 3,5dlmethylphenyl) dlmetlrvlmethane D101 hydroxy 3,5dlmethylphenybdipropylmethane The last six phenols of the above tableare of particular interest in this invention because in the pure statethey have very little if any characteristic odor or tendency todiscolor. These phenols maybe described generally as polycyclic phenolshaving at least two non-condensed carbocyclic nuclei and having the paraposition to their phenolic hydroxyl groups occupied by tertiaryaliphatic carbon atoms.

Non-condensed polycyclic phenols having an alz'cyolic ring Example 1This example illustrates the stabilization of cellulose acetate rayon.Strips of the woven fabric wide were immersed for one hour in aalcoholic solution of p-hydroxydiphenyl. The excess liquid was squeezedout and the treated strips kept side by side with untreated controlstrips of exactly the same size and shape for twenty-four hours at 25 C.and 50% relative humidity. Two of the controls and two of the treatedstrips were then tested for elongation and breaking strength on a Scotttesting machine. The values obtained-approximately the same for bothweretaken as 100%. All of the remaining strips, together with the remainingcontrols, were then exposed to ultra-violet rays under a Cooper-Hewittquartz mercury vapor lamp in order to accelerate the deterioration ofthe fabric. All strips were placed at a distance of approximately 24inches from the lamp where the temperature was approximately 30 C.Exposure was continued for 57 hours. Two control strips and two treatedstrips were removed at the end of 25 hours and 57 hours, then stored at25 C.

and 50% relative humidity for 24 hours, and iinally tested forelongation and breaking strength in the same manner as before exposure.At the end of 25 hours the untreated control retained 7.5% and thetreated fabric 60.3% of the original strength. At the end of 57 hoursthese values were 1.5% and 44.1%, respectively. By this time theuntreated control was very weak, readily torn, and whollyuseless, butthe treated fabric, while definitely weakened, was still usable.

p,p'-Dihydroxydiphenyl, the monomethyl ether of p,p'-dihydroxydiphenyl,di(4-hydroxyphenyl) sulfone, di(4-hydroxyphenyl) ether,di(4-hydroxyphenyl) dimethylmetliane, naphthyl) dimethylmethane, di(4-hydroxyphe nyDphenyl methane, etc., may be used in the above exampleinstead of p-hydroxydiphenyl and good results obtained in retarding theweakening, discoloration and general disintegration of the fabric. Theseagents are also effective with regenerated cellulose, cotton, and paper.While they may be used in the raw material, they are more convenientlyand effectively applied to some di,(4-hydroxymanufacture thereof asviscose rayon (fibers or fabrics), thin transparent sheets ofregenerated cellulose such as those ordinarily used for wrappingpurposes, and cotton or rayon textiles, rope. threads, etc.

As previously pointed out these agents are also effective when thetreated base material is subjected to various temperatures and/or tolight of various types and intensities and/or when aged in the absenceof light, the ultraviolet light merely being used for quick results.

Example 2 Woven viscose rayon fabric was treated with a 5% alcoholicsolution of p-hydroxydiphenyl in the same manner as in Example 1. After36 hours exposure to ultraviolet light under the same conditions as inExample 1, the treated fabric ri. tained 72.7% of its original strengthwhile the untreated control retained only 51.6%. The correspondingfigures at the end of 72 hours were 61.8% and 28.3%.

In the above example the p-hydroxydiphenyl may be replaced bydi(4-hydroxyphenyl) ether, m-hydroxydiphenyl, di (4-hydroxyphenyl)dimethylmethane, di(4-hydroxyphenyl) methyl phenylmethane, di(4-hydroxy-3-methylphenyl) dimethylmethane, etc., and good resultsobtained. That latter three agents are particularly desirable becausethe treated and aged fabric is quite free from the odor of phenol andalso retains its original luster and hue. Phenols not having thecharacteristic p-tertiary carbon atoms frequently tend to discolor undereven normal conditions of exposure and more so in the presence ofconcentrated ultraviolet light. In substituting these agents for thep-hydroxydiphenyl appropriate low boiling solvents which do not attackthe base material should be used in applying these agents. Paper, paperpulp, cotton and cellulose derivatives may also be rendered moreresistant to deterioration by treatment with these alternative agentsafter the general manner of Example 2.

Earample 3 Woven viscose rayon fabric was soaked in a 5% alcoholicsolution of o-hydroxydiphenyl and the treated fabric exposed toultraviolet light together with untreated controls. After 72 hours thetreated fabric possessed 36.7% of its original strength and the controlonly 28.3%.

Example 4 Woven viscose rayon fabric was impregnated with a solution ofp,D'-dihydroxydiphenyl in a mixture of alcohol and toluene of suchconcentration (5-7%) to give about 4% by weight of the stabilizing agentupon the fabric. The solvent was then allowed to evaporate and the drytreated fabric exposed to ultraviolet light together with untreatedcontrols. After 36 hours the former possessed 57.7% of its originalstrength and the control only 51.6%. At the end of 72 hours, thesefigures were 42.3 and 28.3, respectively.

Example 5 ren better results obtained. the treated fabric aving after 36hours, 86.9% of the original rength; Of all the agents tested, the oand-cycloheml phenols gave the best results. This ill be evident from acomparison with the exmples given above.

Example 6 Strips of paper were immersed for one hour in I 10% alcoholicsolution of p-hydroxydiphenyl. he wet strips of paper were then removedfrom 1e impregnating bath and allowed to dry toether with untreatedcontrols for 24 hours at 5 C. and 50% relative humidity; The treated nduntreated paper strips were then exposed to ltraviolet light in themanner of wample 1 ar 6 days. At *the end of this time, both were estedmtensile strength. The control strip roke upon application of 2.6 poundswhile the seated paper-required a tension of 5.0 pounds eiore breaking.Both strips of paper were cut mm the same sheet of paper and were Vride.

It has been found that an impregnation with bout 4% of the stabilizingagentis satisfactory a most instances. The amount required for bestesultslwill, however, vary somewhat depending n the particularstabilizer used and the maerial treated. As a rule, the quantity of thetabilizer should lie within the range 0.25% to .0% based on the weightof material treated. Quantities outside this range are, however, stilliseful and are by no means precluded.

It will be seen irom the preceding examplehat impregnated samples showmarked improvement over the untreated samples in their rerlstance todeterioration as induced or caused my ultraviolet light. It is againdesired to point rut, however, that the ultravioletlight is only anethod for obtaining rapid results. The rate of ieterioration is alsodecreasedmarkedly under ither conditions as, for-example, in the absence3f light and in ordinary sunlight. In other words, the present agentsare 'efiective in retar-ding the deterioration of cellulosic substanceswhen subjected to light of diflerent types and intensities.

It will be noted that all the systems in which the presentagents areused are closely related. Regenerated cellulose, cellulose ethers oresters, and manufactures of both, all have a greater or less number ofunsubstituted or partially substituted (i. e., etherifled or esteriiied)glucose units ioined together in a complexjashion. It seems reasonableto suppme that the tendency of cellulosic materials to deterioration onaging may be due to disruption of the bonds between glucose units and/orthe rearrangement of these units or building stones to a more degradedstructure. Thus the systems in which these agents are used not only havea common and distinctive chemical relation irrespective of the processesor the invention, but all these systems are probably aiiected similarlyby all of the agents of this invention.

As many apparently widely different embodi ments of this invention maybe made without departing from the spirit and scope thereof, it is to beunderstood that there are nospecifio limiting embodiments except asdefined in the ap pended claims. J

We claim:

1. Paper impregnated with 0.25% to 5.0% o! a polycyclic phenol having atleast two non-condensed carbocyclic nuclei. 7

2. The process of rendering paper more resistant to the deleteriouseflect of aging which 0021- sists in impregnating its fibrous mass with0.25% to 5.0% of a polycyclic phenol having at least two non-condensedcarbocyclic nuclei.

3. The process of rendering cotton and fabricated cotton more resistantto the deleterious eiiect of aging which consists in depositing on thefibrous surfaces 0.25% to 5.0% of a polycyclic phenol having at leasttwo non-condensed car'- bocyclic nuclei. 7 4. The process of. renderingregenerated cellulose fibres and fibrous manufactures thereof moreresistant to the deleterious eflects of using which consists indepositing on the fibrous surfaces 0.25% to 5.0% oi a polycyclic phenolhaving at least two non-condensed carbocyclic nuclei.

5. Fibres and fibrous manufactures'thereof of the group consisting ofcellulose and regenerated cellulose having deposited on the fibroussurfaces 0.25% to 5.0% oi a polycyclic phenol having at least twonon-condensed carbocyclic nuclei.

6. Cotton and fabricated cotton having deposited on the fibrous surfaces0.25% to 5.0% of a polycyclic phenol having at least two non-condensedcarbocyclic nuclei. 7. Fibres of regenerated cellulose and manuiacturesthereof having deposited on the fibrous suriaces,0.25% to 5.0% of apolycyclic phenol having at least two non-condensed carbocyclic nuclei.

JAMES KARE HUNT. GEORGE HENRY LATHAM.

